Thin transfer film for ultrafine electrodes of solar cells, manufacturing process and application process for it

Abstract

Hyperfine electrode transfer film for a solar cell, wherein the electrode transfer film comprises, from bottom to top, a substrate (10), a separating layer (20), a resin layer (30) and a hot melt adhesive layer (40), electrode slots (31) are formed in the resin layer (30) and electrodes (50) are formed in the electrode slots (31), wherein the separating layer (20) comprises a coating that enables separation between the substrate (10) and the resin layer (30), wherein there is no or low tackiness between the separating layer and the resin layer.

Description

SPECIALIZATION

[0001] The present disclosure relates to the technical field of solar cells and in particular to a hyperfine electrode transfer film for a solar cell, a method for manufacturing the same and a method for using the same. BACKGROUND

[0002] Monocrystalline silicon and polysilicon solar cells are typically manufactured by applying surface electrodes to a silicon surface using a precise screen printing process. These electrodes usually have a conductor track width of 60 µm to 100 µm. With a 60 µm conductor track width, clogging can occur due to the properties of the printing screen and the electrically conductive suspension, negatively impacting the yield and quality of the electrodes. Furthermore, electrodes with a larger conductor track width have two disadvantages: high consumption of electrically conductive suspension, resulting in high costs, and a large surface area of ​​the surface electrodes on the silicon chip, which reduces the photoelectric conversion efficiency of the cell.It is therefore important to reduce the conductor track width of the surface electrodes, decrease the consumption of electrically conductive suspension, and increase the light-absorbing area of ​​the cell.

[0003] The production of surface electrodes for solar cells is limited by the following factors: compatibility with existing processes for solar cells, ease of implementation, support for efficient processing, lower compound costs than the costs of screen printing (including costs for the printing screen and the electrically conductive suspension), and ease of mass production of the material.

[0004] In a method for manufacturing a front electrode for a solar cell, disclosed in Chinese patent application number 201080023219.3, which is also a PCT application, an electrode is formed by filling a pattern-printed mold, then transferred from the mold using an adhesive film and fused to a semiconductor substrate. The PDMS mold used in the disclosure is soft and therefore delicate, and the electrode has a conductor track width of over 20 µm; therefore, directly fusing the electrode to the semiconductor substrate would create problems with regard to production efficiency and environmental control.

[0005] To solve the problems mentioned above, it is necessary to provide a hyperfine electrode transfer film for a solar cell, a method for manufacturing it, and a method for using it.

[0006] From US Patent 5,992,320 A, a transfer film is known that is suitable for forming high-precision patterns for electrode layers, dielectric layers, barrier layers, etc. The transfer film comprises a carrier film with a concave pattern formed on one side and a lacquer layer that is filled into a portion of the carrier film having the concave pattern. The lacquer layer consists of an inorganic component comprising at least one glass frit and a resin component that can be removed by firing. Patent Publication Number US 2013 / 0032204A1 discloses a transferable layer containing a grid on a photovoltaic cell. SUMMARY

[0007] In light of the above, a hyperfine electrode transfer film for a solar cell, a method for manufacturing it, and a method for applying it are provided to solve the problems of conventional technology.

[0008] To achieve the above-mentioned objective, the following technical solutions are provided in accordance with the embodiments of the present disclosure.

[0009] A hyperfine electrode transfer film for a solar cell is provided, wherein the electrode transfer film comprises, from bottom to top, a substrate, a separating layer, a resin layer and a hot melt adhesive layer, electrode slots are formed in the resin layer and electrodes are formed in the electrode slots.

[0010] In a further advantageous development, the electrode slots and the electrodes have a comb-like structure or a honeycomb structure that corresponds to the solar cell.

[0011] In a further advantageous development, the electrodes are made from a mixed material consisting of micro glass bead frit and electrically conductive suspension.

[0012] In a further advantageous embodiment, the separating layer has a thickness of 0.5 µm to 1.2 µm, and the hot melt adhesive layer has a thickness of 0.5 µm to 2.0 µm.

[0013] In a further advantageous development, each of the electrode slots has a conductor track width of 2 µm to 50 µm and a depth of 2 µm to 60 µm.

[0014] In a further advantageous development, each of the electrode slots has a conductor track width of 10 µm to 30 µm.

[0015] Accordingly, a process for manufacturing a hyperfine electrode transfer film for a solar cell includes: S1, providing the substrate; S2, Application of the separating layer to the substrate; S3, Applying the resin layer to the separating layer and forming the electrode slots by printing them onto the resin layer with a convex shape corresponding to an electrode structure, wherein the conductor width and depth of each of the electrode slots are adapted based on the requirements for the electrical conductivity of the electrode; and S4, forming the electrodes by filling the electrode slots with electrically conductive suspension and baking, and applying the hot melt adhesive layer to the electrodes.

[0016] In a further advantageous advanced training, the training of the electrodes in step S4 includes: Filling the electrode slots with glass frit and electrically conductive suspension and sintering at a low temperature of less than 150°C.

[0017] In a further advantageous embodiment, filling the electrode slots with glass frit and electrically conductive suspension comprises: filling the electrode slots with the glass frit and the electrically conductive suspension at the same time; or first filling the electrode slots with the glass frit and then with the electrically conductive suspension.

[0018] Accordingly, a method for applying the hyperfine electrode transfer film to a solar cell includes: Attaching the hot melt adhesive layer of the electrode transfer foil to an anti-reflective layer on a surface of the solar cell and heating to bond the hot melt adhesive layer to the anti-reflective layer; Removing the separating layer and substrate to connect the transparent electrodes to the surface of the solar cell; and Sintering at high temperature to evaporate the hot melt adhesive layer, fuse the electrodes with the surface of the solar cell, and fully transfer the hyperfine transparent electrodes.

[0019] In the present disclosure, roll-to-roll nanoimprinting is used, conductive electrodes are continuously produced on a transparent film and transferred as a whole, and substandard transfer does not occur locally. Furthermore, the hot melt adhesive layer and the semiconductor substrate are directly sintered at high temperature to vaporize the hot melt adhesive layer and preserve the electrodes, thereby achieving reliability, high efficiency, and ease of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are necessary for describing the embodiments or the conventional technology, are briefly described below so that the technical solutions according to the embodiments of the present disclosure or in the conventional technology become clearer. It is obvious that the accompanying drawings in the following description represent only some embodiments of the present disclosure. For a person skilled in the art, other accompanying drawings can be derived without any creative effort. Fig. Figure 1 is a structural representation of an electrode transfer foil of the present disclosure; Fig. Figure 2 is a structural representation of electrodes having a comb-like structure according to one embodiment of the present disclosure; and Fig. Figure 3 is a structural representation of electrodes having a honeycomb structure according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE DRAWINGS

[0021] The following describes embodiments in detail in conjunction with the accompanying drawings. However, these embodiments are not intended to limit the disclosure. Any modifications to the structure, method, or function made by a person skilled in the art based on these embodiments fall within the scope of protection of this disclosure.

[0022] A hyperfine electrode transfer film for a solar cell is disclosed. Referring to Fig. 1 The electrode transfer foil comprises, from bottom to top, a substrate 10, a separating layer 20, a resin layer 30 and a hot melt adhesive layer 40. Electrode slots 31 are formed in the resin layer 30 and electrodes 50 are formed in the electrode slots 31.

[0023] The layers of revelation are described below.

[0024] Substrate 10 usually consists of a plastic film or a piece of paper.

[0025] The release layer 20 comprises a coating that enables surface separation. To increase the release force of the plastic film or paper, the release layer is typically formed by applying a plasma or fluorination process to the plastic film or paper, or by applying a silicon release agent to a surface of the coating material. There is no or minimal tackiness between the release layer and a specific material brought into contact with it under controlled conditions.

[0026] In the present disclosure, the separating layer is arranged to separate the resin layer 30 and the hot melt adhesive layer 40 from the substrate 10. Preferably, the separating layer has a thickness of 0.5 µm to 1.2 µm.

[0027] The resin layer 30 is made of UV-sensitive resin. The electrode slots 31 are formed by printing onto the resin layer with a convex shape corresponding to an electrode structure. The electrode slots 31 are designed to develop the electrodes 50. Preferably, each electrode slot has a conductor width of 2 µm to 50 µm and a depth of 2 µm to 60 µm. Preferably, the electrode slots have a typical conductor width of 10 µm to 30 µm. The electrodes are made of a mixture of glass frit and electrically conductive suspension. The electrodes are preferably in the form of a silver conductor and, in other embodiments, can be made of metallic material in the form of a gold or copper conductor.

[0028] Referring to Fig. 2 and Fig.3 The electrode slots 31 and the electrodes 50 can accordingly have a comb-like structure or a honeycomb structure.

[0029] The hot melt adhesive layer 40 is vaporized after being sintered at high temperature. The hot melt adhesive layer 40 preferably has a thickness of 0.5 µm to 2 µm.

[0030] A method for producing a hyperfine electrode transfer film for a solar cell is also provided in the present disclosure. The method comprises steps S1 to S2.

[0031] In step S1, substrate 10 is provided.

[0032] In step S2, the separating layer 20, which has a thickness of 0.5 µm to 1.2 µm, is applied to the substrate 10.

[0033] In step S3, the resin layer 30 is applied to the separating layer 20, and the electrode slots 31 are formed by printing a convex shape, corresponding to an electrode structure, onto the resin layer 30. The electrode slots 31 and the electrodes 50 have a comb-like or honeycomb structure. The conductor width and depth of each electrode slot are adapted based on the electrical conductivity requirements of the electrode.

[0034] In step S4, the electrodes 50 are formed by filling the electrode slots 31 with electrically conductive suspension and baking, and the hot melt adhesive layer 40, which has a thickness of 0.5 µm to 2 µm, is applied to the electrodes.

[0035] The electrodes in step S2 are formed by filling the electrode slots with the glass frit and the electrically conductive suspension by brushing and sintering (baking) at a low temperature of less than 150°C.

[0036] Furthermore, the glass frit and the electrically conductive suspension are filled simultaneously, or the glass frit is filled first and then the electrically conductive suspension is added. Preferably, the proportion of the mass of the electrically conductive suspension is 80%, although this proportion may differ in other embodiments.

[0037] In the present disclosure, a method for applying the hyperfine electrode transfer film for a solar cell comprises the following steps: Attaching the hot melt adhesive layer of the electrode transfer film to an anti-reflective layer on the surface of a solar cell and heating to bond the hot melt adhesive layer to the anti-reflective layer; Removing the separating layer and substrate to connect the transparent electrodes to the surface of the solar cell; and Sintering at high temperature to evaporate the hot melt adhesive layer, fuse the electrodes with the surface of the solar cell, and fully transfer the hyperfine transparent electrodes.

[0038] For the hyperfine electrode transfer film for a solar cell, the method for its fabrication, and the method for its application as described in the present disclosure, roll-to-roll nanoimprinting is employed. Conductive electrodes are continuously produced on a transparent film and transferred as a whole, and localized degradation of the transfer is avoided. Furthermore, the hot melt adhesive layer and the semiconductor substrate are directly sintered at high temperature to vaporize the hot melt adhesive layer and preserve the electrodes, thereby achieving reliability, high efficiency, and ease of application.

[0039] In the present disclosure, the cell can be a solar cell, but is not limited to such. The solar cell can be a thin-film cell made of amorphous silicon or microcrystalline silicon, a CIGS cell, a dye-sensitized solar cell, an organic solar cell, a gallium arsenide cell, and the like, but is not limited to these.

[0040] In summary, the technical solutions in the present disclosure have the following advantages over conventional technology.

[0041] The electrodes are continuously produced on a transparent film by roll-to-roll nanoimprinting; the electrodes are transferred as a whole, and inferior transfer will not occur locally.

[0042] The hot melt adhesive layer and the semiconductor substrate are sintered directly at high temperature to evaporate the hot melt adhesive layer and preserve the electrodes, thereby achieving reliability, high efficiency and ease of use.

[0043] A conductor track width of less than 30 µm can be achieved and the area coverage of the electrodes on the surface of a silicon chip is reduced by at least 50%.

[0044] Furthermore, the electrodes, which have a honeycomb structure, can reduce the distance over which a current is transferred from the solar cell to the electrodes, as well as the recombination rate of the charge carriers, and is advantageous to improve the conversion efficiency.

Claims

[1] Hyperfine electrode transfer film for a solar cell, wherein the electrode transfer film comprises, from bottom to top, a substrate (10), a separating layer (20), a resin layer (30) and a hot melt adhesive layer (40), electrode slots (31) are formed in the resin layer (30) and electrodes (50) are formed in the electrode slots (31), wherein the separating layer (20) comprises a coating that enables separation between the substrate (10) and the resin layer (30), wherein there is no or low tackiness between the separating layer and the resin layer. [2] Hyperfine electrode transfer film for a solar cell according to claim 1, wherein the electrode slots (31) and the electrodes (50) have a comb-like structure or a honeycomb structure corresponding to the solar cell. [3] Hyperfine electrode transfer film for a solar cell according to claim 2, wherein the electrodes (50) are made of a mixed material of micro glass bead frit and electrically conductive suspension. [4] Hyperfine electrode transfer film for a solar cell according to claim 1, wherein the separating layer (20) has a thickness of 0.5 µm to 1.2 µm and the hot melt adhesive layer (40) has a thickness of 0.5 µm to 2.0 µm. [5] Hyperfine electrode transfer film for a solar cell according to claim 1, wherein each of the electrode slots (31) has a conductor width of 2 µm to 50 µm and a depth of 2 µm to 60 µm. [6] Hyperfine electrode transfer film for a solar cell according to claim 5, wherein each of the electrode slots (31) has a conductor width of 10 µm to 30 µm. [7] Method for producing the hyperfine electrode transfer film for a solar cell according to any one of claims 1 to 6, comprising: S1, providing the substrate (10); S2, Applying the separating layer (20) to the substrate (10); S3, applying the resin layer (30) to the separating layer (20) and forming the electrode slots (31) by printing them onto the resin layer (30) with a convex shape corresponding to an electrode structure, wherein the conductor width and depth of each of the electrode slots (31) are adapted based on the requirements for the electrical conductivity of the electrode (50); and S4, forming the electrodes (50) by filling the electrode slots (31) with electrically conductive suspension and baking, and applying the hot melt adhesive layer (40) to the electrodes (50). [8] Method according to claim 7, wherein forming the electrodes (50) in step S4 comprises: Filling the electrode slots (31) with glass frit and electrically conductive suspension and sintering at a low temperature of less than 150°C. [9] Method according to claim 8, wherein filling the electrode slots (31) with glass frit and electrically conductive suspension comprises: Filling the electrode slots (31) with the glass frit and the electrically conductive suspension at the same time; or First, the electrode slots (31) are filled with the glass frit and then with the electrically conductive suspension. [10] Method for applying the hyperfine electrode transfer film for a solar cell according to any one of claims 1 to 6, comprising: Providing a hyperfine electrode transfer film for a solar cell, wherein the electrode transfer film comprises, from bottom to top, a substrate (10), a separating layer (20), a resin layer (30) and a hot melt adhesive layer (40), electrode slots (31) are formed in the resin layer (30) and electrodes (50) are formed in the electrode slots (31); Attaching the hot melt adhesive layer (40) of the electrode transfer foil to an anti-reflective layer on a surface of the solar cell and heating to bond the hot melt adhesive layer (40) to the anti-reflective layer; Removing the separating layer (20) and the substrate (10) to connect the transparent electrodes (50) on the surface of the solar cell; and Sintering at high temperature to evaporate the hot melt adhesive layer (40), to fuse the electrodes (50) with the surface of the solar cell and to fully transfer the hyperfine transparent electrodes (50).

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